ISTANBUL/AMSTERDAM (Reuters) - A prominent Dutch journalist has been detained by Turkish police while on holiday, Dutch officials said on Sunday, a week after she criticized President Tayyip Erdogan in print for clamping down on dissent.

Columnist Ebru Umar, who is of Turkish descent and an outspoken critic of Erdogan, was detained by police overnight in Turkey where she was on holiday. She tweeted on Sunday that she had been released but was not allowed to leave the country.

In the free newspaper Metro last week, Umar called Erdogan a "dictator" and criticized a Turkish consular official in the Netherlands for asking all Turks there to report incidents of insults against Erdogan in the country. The call was widely criticized and later withdrawn.

Erdogan is known for his readiness to take legal action over perceived slurs. At his behest, prosecutors in Germany are pursuing a comedian for mocking him. Critics say Erdogan uses the courts to stifle dissent.

Dutch Prime Minister Mark Rutte, who joined the criticism of the Turkish official's call, said he had spoken with Umar after her arrest. "Had telephone contact with Ebru Umar last night," he said on his official Twitter account on Sunday.

A Dutch foreign ministry spokesman said of her detention: "We are aware of this and we are following the situation closely. We are in contact with her."

"NO JOKE"

On her official Twitter account, Umar tweeted overnight: "Police in front of the door. No joke." She later tweeted that she was being taken to a police station in Kusadasi, a resort town on Turkey's Aegean coast.

"Free but under country arrest," she said in a tweet on Sunday afternoon, her first since her arrest 15 hours earlier.

Umer's Twitter feed showed she had recently engaged in spirited exchanges with her critics on Twitter. She reposted a tweet from someone claiming to have reported her to the police.

Insulting the president is a crime in Turkey punishable by up to four years in jail, but the law had previously been invoked only rarely. Since Edogan became president in 2014, prosecutors have opened more than 1,800 cases against people for insulting him, the justice minister said last month.

Those who have faced such suits include journalists, cartoonists, academics and even school children. Erdogan has said he is open to criticism, but draws the line at insults.

Germany has decided to allow prosecutors to pursue a case against a German comedian who mocked Erdogan. This decision has angered many Germans, who see it as a sop by Chancellor Angela Merkel to an authoritarian leader.

Last year, Turkey deported another Dutch journalist after she was detained on suspicion of aiding Kurdish militants.

Born in The Hague to Turkish parents, Umar has been an outspoken critic of militant Islam, first in columns for the website of Theo van Gogh, who was murdered by a radical Islamist in 2004 after making films critical of the religion.

Writing in Metro and the critical website GeenStijl, she has denounced headscarves, excessive noise from mosques and what she sees as excessive Dutch tolerance, attracting bulging bags of hate mail from furious critics.